Aftertreatment with an aldehyde of wool dyed with chromed azo dyes



Patented July 25, 1950 AFTERTREATMEN T WITH AN ALDEHYDE-OF WOOL- DYED WITH CHROMED AZO DYES Willy Widmer, Bottmingen, and Arthur Buehler, Rheinfelden', Switzerland, assignors to Ciba Limited, Basel, Switzerland, a *Swiss firm No Drawing. Application October 4, 1948, Serial No. 52,793. ,In.SwitzerlandNovember 4, 1947 It is known that in dyeing with'metalliferous acid monoazo-dyestuffs, which contain in'orthoposition to the azo-linkagean amino. group and a hydroxyl group, it is of advantage to carry out the dyeing with the addition of a lower aliphatic aldehyde, especially formaldehyde or a substance yielding formaldehyde, Many dyestuffs of that kind have the undesirableproperty, even in dyeing inthe usual manner fromia sulfuric acid bath,'but especially with the prolonged dyeing periods, of yielding dull and unsightly dyeings, which is due to decomposition, probably .a partial demetallisation of the dyestuff. The prior proposals (see United States Patent No. 2,422,586) state that the aldehyde present in the -.dy.ebath.has the effect of inhibiting to agreat extent the aforesaid decomposition of the dyestufi-metal complex. Obviously this action of inhibiting decomposition can occur only when the formaldehyde or a-compound of similar action is present in the dyeoath in sufficient quantity during dyeing. As the dyeing process-must be conducted at a high temperature (usually at the boil) in Order to fix the aforesaid dyestufis there is a continuous loss of easily volatile formaldehyde, andalsc considerable difficulties may arise in the dye works due to the odor evolved. I

The present inventionis based on the unexpected I observation that by after treating with .an aldehyde dyeings, which haveibeen produced with acid dyestufis containing an ortho-amino-orthohydroxy-azogrouping in the metallized condition, there are obtained results as good as those obtained when an aldehyde is :added to the dyebath. There is no obvious explanation for this phenomenon. It can only be supposed that the aldehydes exert a selective'decomposing or stripping action on the dyestuii decomposition products formed during the dyeing process, without materially afiecting the metal complex proper. However, it is not known that aldehydes can exhibit an action of this kind and it could not be foreseen that they would do so.

As compared with the known process in which the aldehyde must be present in the dyebath in sufficient quantity throughout the wholeof the dyeing operation, the process of the present invention has obvious advantages. The present process enables the aldehyde, especially the relatively inexpensive formaldehyde, to be used at alower temperature or, which is an important advantage, for a shorter period of treatment, and, if desired, in apparatus which is not suitable for dyeing.

There are known a large number of dyestuffs, especially monoazo-dyestuffs and complex metal may be car-ried out inknown mannen-forexample,

11 Claims. (01. 8-43) :compounds thereof, which are suitable 'for the production of dyeings to be after-treated in accordance with the present invention. For example, they ma be derived, on the one hand,

from azo compounds capable of coupling in orthoposition'to an amino group, especially to Z-aminonaphthalene and sulfonic acids thereof, and, 'on the other, from ortho-hydroxy-diazo-compounds, care being taken that at least one sulfo group is present in'at least one of the two components so that the resulting dyestufi is suitable for dyeing from an acid bath. As coupling components there come into consideration, for example, '2- aminonaphthalcne, Z-aminonaphthalene-B- or -6- or-7-sulfonic acid, or 2-amino-naphthalene- 3:6- or -5:7-disulfonic acid. As diazo-coinpodroxybenzenes free from further substituents andf2eaminonap'hthalene sulfonic acids. Thus, for example, in the case of dyestuffs from 2- amino-S-nitrml-hydroxybenzene and 2-aminonaphthalene 5- or-6- or -"7-sulfonic acid or 2- amino naphtl'lalc-rne-5:7- or -3:6-disulfonic acid,.

andalso in the case of dyestuiis derived from "2- an'iino-1hydroxybenzene-4-sulfonic acid or 2- amino a l cliloro -l hydroxy'oenzene 6-su1fonic acid or z-am'ino-f l-methyl-1-hydroXybenzene-5- or -6-su1fonic acid and. z aminonaphthalene.

The dyeings to be after-treated in accordance with the present invention are produced withcomplex :chromium compounds of the foregoing dyestufis, which have been prepared in substance and contain one atom of chromium per orthoamino-orthof ehydrox-y-azo-grouping. The dyeing temperature if desired with the addition =of-a salt l 8110112315 sodiumisulf ate.

For after-treating .such dyeings [in accordance Those dyestuffs of an ordinary commercial aqueous solution or in the form of polymerization or condensation products yielding the aldehyde. In the latter connection there may be mentioned polymerized acetaldehyde, paraformaldehyde, condensation products of amines or phenols with formaldehyde which contain the formaldehyde in;loose combination such as melamine-formaldehyde condensation products or urea-formaldehyde condensation products having a high content of formaldehyde.

There also come into consideration aldehydes which are derived from organic radicals of high molecular weight and contain the aldehyde group bound to a heterocyclic'pr carbocyclic, advantageously aromatic, ring such as furfural, phthalaldehyde, salicylaldehyde, and the like. Furthermore, in some casesthere may be used with advantage aldehydes which contain besides the aldehyde group at least one ionisableacid group, suchtas benzaldehyde monoor di-sulfonic acids or monoor di-carboxylic acids. As examples there may be mentioned benzaldehyde -2- or -3- or -4-sulfonic acid, 4-nitro-benzaldehyde-2-sulfonic acid and benzaldehyde-2:4- or -2:5-disulfonic acid, and also benzaldehyde-Z- or -3- or -4 carboxylic acid. There are also suitable for the present invention aldehydes which, owing to the presence of a basic group, are capable of forming water-soluble salts with mineral acids, especially sulfuric acid. S-aminobenzaldehyde is an example of such an aldehyde.

The after-treatment of the aforesaid dyeings may be applied at any time after the whole or at least the greater part of the dyeing process has been carried out. The after-treatment may therefore be carried out in the dyebath itself, if

desired after it has cooled somewhat, or in a fresh bath with or without intermediate drying of the material. By the use of a fresh bath the aftertreatment bath can be maintained acid, and advantageously strongly acid, by the addition of an acid, for example, sulfuric acid.

The proportion of the aldehyde to be used in the after-treatment of this invention may vary within wide limits, since a small addition of about 0.5 per cent. generally has acertain effect and large additions of about 10 or more percent. do not as a rule have a deleterious efiect. In many cases an addition of 1-6 per cent. of formaldehyde or 2-8 per cent. of a benzaldehyde sulfonic acid is of advantage.

The after-treatment may be conducted in an aqueous .bath at a moderately raised temperature, for example, about 40-50 0., .for a period. ranging from one to several hours. At higher temperatures in the region of 90-100 C. considerably shorter periods of treatment give the result, for example, a period of treatment of 15 minutes.

In the case of easily volatile aldehydes such as Iormaldehyde r benzaldehyde, the after-treatment may also be carried out by subjecting the dyed and, if desired, dried material for a lon time to the action of the vapor of the aldehyde. Provided that the period of treatment is sufficiently long this method of after-treatment leads to a quite substantial improvement in the dyeing even when it is carried out at room temperature. In order to avoid losses of aldehyde and troubles due to odors the'process is advantageously carried'out-in a closed space (a steam chamber).

The following examples illustrate the invention, the parts being by weight:

Example 1 100 partsof Wool are dyed in the usual manner with 1.5 parts of the complex chromium compound of the dyestufi from diazotized 5-nitro-2- amino-l-hydroxybenzene and 2-amino-naphthalene-G-sulfonic acid from a dyebath which contains 8 parts of sulfuric acid and 10 parts of crystalline sodium sulfate. When the dyeing is finished there are added to the hot dyebath at 98-100" C. 5 parts of an aqueous formaldehyde solution of 40 per cent. strength and the bath is maintained at 98-100 C. for a further 15 minute's. The wool is then rinsed and finished in the usual manner. A level pure yellowish green dyeing is obtained.

By using instead of formaldehyde 2 parts of para-formaldehyde or 5 parts of a water-soluble condensation product of formaldehyde and melamine, there is likewise obtained a pure yellowish green wool dyeing.

Example 2 act for one hour at IOU-90 C. Then the wool chromium compound of the dyestuff from diazois rinsed and finished in the usual manner.

There is obtained a green wool dyeing which is substantially purer and of a more yellow shade than that which is obtained without after-treatment with benzaldehyde-3-sulfonic acid.

Example 3 i 100 parts of wool are dyed in the usual manner with 1.5 parts of the complex chromium compound of the dyestuff from diazotized 4- chloro-2-amino-l-hydroxybenzene 6 sulfonic acid and Z-aminonaphthalene from a dyebath which contains 8 parts of sulfuric acid and 10 parts of crystalline sodium sulfate. When the dyeing is finished there is added to the hot dyebath at 98-100 C. 1 part of formaldehyde and the bath is maintained at that temperature for one hour. The wool is then rinsed and finished. It is dyed a level, pure, blue-green tint. Without the after-treatment with formaldehyde the dye- .ing would be considerably duller.

Example 4 100 parts of wool are dyed in the manner described in Example 1 with 1.5 parts of the complex tized 5-nitro-2-amino-l-hydroxybenzene and 2- aminonaphthalene-6-sulfonic acid. When the dyeing is finished the wool is rinsed and entered into a fresh bath at 6070 C. This fresh bath is mixed with the dilute sulfuric acid solution of benzaldehyde-B-sulfonic acid, which contains 1 part of the said sulfonic acid and 8 parts of sulfuric acid. The bath is slowly raised to the boil and then maintained at 98-100 C. for 1 hour.

. The'wool'is then rinsed and finished in the usual manner. It is dyed a uniform pure yellowish green tint. Without the after-treatment with benzaldehyde-S-sulfonic acid a considerably bluer and duller dyeing would be obtained.

Instead of the sulfuric acid solution of benzaldehyde-3-sulfonic acid, there may be added tothe after-treatment bath a solution of 1.5 parts of 3-aminobenzaldehyde in 80 parts of sulfuric acid of per cent. strength, the procedure being the same in other respects. In this case also a pure yellowish green dyeing is obtained.

Example 5 100 parts of wool are dyed in the manner described in Example 1 with 1.5 parts of the complex chromium compound of the dyestuff from diazotized 5-nitro-2-amino 1 hydroxybenzene and 2-aminonaphthalene-G-sulfonic acid. When the dyeing is finished the wool is rinsed and dried. The wool so dyed is suspended in a closed chamber at room temperature. is saturated with formaldehyde vapor. This is brought about by inserting in the lowest part of the chamber, (for example in a flat dish) an aqueous solution of formaldehyde of 40 per cent. strength. The wool should not come into contact with the formaldehyde solution. The wool is kept in the chamber at room temperature for 18 hours. At the end of this period the previously bluish, dull dyeing is a pure yellowish green.

Similar results are obtained by suspending for 18 hours in a closed chamber over a formaldehyde solution, instead of dry wool, moist wool, for example as it is obtained after dyeing and rinsing. Instead of formaldehyde solution ordinary commercial benzaldehyde may be used for the treatment of the moist wool, the action of benzaldehyde on dry wool being considerably slower.

What we claim is:

1. A process for after-treating dyeings produced on wool with acid dyestuffs containing an ortho-amino-ortho -hydroxy-azo-grouping in the chromed condition, wherein the dyeing is treated with an aldehyde.

2. A process for after-treating dyeings produced on wool with acid dyestuffs containing an ortho-amino-ortho'-hydroxy-azo grouping in the chromed condition, wherein the dyeing is treated with a lower aliphatic adehyde.

3. A process for after-treating dyeings produced on wool with acid dyestuffs containing an ortho-amino-ortho'-hydroxy-azo grouping in the chromed condition, wherein the dyeing is treated with a lower aliphatic aldehyde which is used in the form of a condensation product or polymerization product capable of yielding said aldehyde.

4. A process for after-treating dyeings produced on wool with acid dyestuffs containing an ortho-amino-ortho-hydr0xy-azo grouping in the chromed condition, wherein the dyeing is treated with formaldehyde.

The closed chamber 5. A process for after-treating dyeings produced on wool with acid dyestuffs containing an ortho-amino-ortho'-hydroxy-azo grouping in the chromed condition, wherein the dyeing is treated with formaldehyde which is used in the form of a condensation or polymerisation product capable of yielding formaldehyde.

6. A process for after-treating dyeings produced on wool with acid dyestuffs containing an ortho-amino-ortho'-hydroxy-azo grouping in the chromed condition, wherein the dyeing is treated with an aldehyde containing an ionisable acid group.

7. A .process for after-treating dyeings produced on wool with acid dyestuffs containing an ortho-amino-ortho'-hydroxy-azo grouping in the chromed condition, wherein the dyeing is treated with an aromatic aldehyde sulfonic acid.

8. A process for after-treating dyeings produced on wool with acid dyestuffs containing an ortho-amino-ortho-hydroxy-azo grouping in the chromed condition, wherein the dyeing is treated with a benzaldehyde sulfonic acid.

9. A process for after-treating dyeings produced on wool with acid dyestuffs containing an ortho-amino-ortho'-hydroxy-azo grouping in the chromed condition, wherein the dyeing is treated with benzaldehyde-3-sulfonic acid.

10. A process for after-treating dyeings produced on wool with acid dyestuffs containing an ortho-amino-ortho'-hydroxy-azo grouping in the chromed condition, wherein the dyeing is treated with a mineral acid salt of an aldehyde containing a basic group.

11. A process for after-treating dyeings produced on wool with acid dyestuffs containing an ortho-amino-ortho-hydroxy-azo grouping in the chromed condition, wherein the dyeing is treated with sulfate of 3-aminobenzaldehyde.

WILLY WIDMER. ARTHUR BUEHLER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,263,894 Sparks Nov. 25, 1941 2,422,586 Royer June 17, 1947 FOREIGN PATENTS Number Country Date 502,314. France Feb. 19, 1920 596,888 Germany May 12, 1934 

1. A PROCESS FOR AFTER-TREATING DYEINGS PRODUCED ON WOOL WITH ACID DYESTUFFS CONTAINING AN ORTHO-AMINO-ORTHO''-HYDROXY-AZO-GROUPING IN THE CHROMED CONDITION, WHEREIN THE DYEING IS TREATED WITH AN ALDEHYDE. 